Cycles bump node: change the Strength value to work better, previously it would
give results that were either too weak or too strong, this makes it give more
predictable results. The downside is that it breaks backwards compatibility but
the previous behavior was almost broken.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56621 954f8c5b-7b00-dc11-b283-0030488c597c
Cycles OpenCL: a few fixes to get things compiling after kernel changes,
for Apple OpenCL on OS X 10.8 and simple AO render.

Also environment variable CYCLES_OPENCL_TEST can now be set to CPU, GPU,
ACCELERATOR, DEFAULT or ALL values to test particuler devices.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56622 954f8c5b-7b00-dc11-b283-0030488c597c